10 § ^' REAGENTS. 



sulphate is precipitated, and then decanting the clear su- 

 pernatant liquid for use. 



i. Acid, silicic. — See Quartz. 

 h. Acid, tannic, needs no testing. 



2, Alcoliol.— C^H^O. (C,H,0,.)— This is used both in 

 its pure state (absolute alcohol), and mixed with water, 

 until its specific gravity is 0.83 or 0.84, corresponding 

 to about 90° I ^ of pure alcohol, by volume. 



It should be volatilized completely, and leave no odor 

 of fusel oil when rubbed between the hands ; it should 

 burn with a pale blue, barely visible flame, and should 

 not redden blue litmus-paper. 



3. a. — Amnionic acetate. — NH.CJIgO^. (Acetate of 



ammonia. NHp,C,H303. NH,0,A.)— This should be 

 colorless, free from empyreumatic odor, and inorganic 

 acids, and should be comj^letely volatilized when heated. 



h. Amnionic carbonate.— (NH J 2CO3. (Carbonate of 

 ammonia. NH40,C02.) — This should be completely 

 volatilized Avhen heated, and, after supersaturation with 

 nitric acid and heating, should give no reaction with solu- 

 tions of silver, barium, or ammonic sulphide. Dissolve it 

 in 4 parts of Avatcr, and add 1 part of ammonia. Keep 

 some of the salt also in the dry form. 



c. Ammonic Cllloridc. — NH^Cl. (Chloride of ammo- 

 nium.) — ^This should be completely volatilized when heated 

 on platinum foil, and should give no reaction with am- 

 monic sulphide, baric chloride, or litmus. Dissolve in 8 

 parts of water. Keep some of the salt also in the form 

 of a dry powder. 



d. Ammonic fluoride.— NH^F. (Fluoride of ammonium.) 

 — This, when heated in a platinum dish, should leave no 

 residue; if impure, it may be purified by sublimation 

 between two platinum dishes. It should be kept in gutta 

 percha bottles. 



